The present invention relates to mining machines in general and in particular to an improved cutter head for a mining machine which is so constructed that it allows the cutting head to be disassembled and repaired where the mining is taking place.
Continuous mining machines are characterized by a cutting head at the front end of the machine, gathering means to collect the mined material, also disposed at the front end of the mining machine, and conveying means to move the mined material to the rear of the mining machine to be discharged to a car or other conveyance for moving the material out of the mine. The cutting head is adapted to be advanced into the mine face and is operated in and over the mine face to cut and break the material out of the mine face. The mined material falls to the mine floor and is collected by the gathering means and swept into the conveyor of the machine. The conveyor extends longitudinally from the front end of the mining machine to the rear end of the machine and moves the material along the machine and discharges the material at the rear end of the machine. The mining machine, of course, is equipped with suitable traction means which may be endless crawler traction treads by which the machine is propelled. Such traction means propells the mining machine forwardly to advance the cutting head into the mine face.
The prior art continuous mining machines have two motors which are disposed, one on each side of the machine and provide the power for operating the several mechanisms of the machine. The motors are continuously operated to provide a continuous source of power during the operation. There is a mechanical transmission driving means from the motors to the cutting head by which the cutting head is driven.
The mining machine has a frame assembly pivotally attached thereto and the cutting head is mounted on the outer end thereof along with the drive motors and the transmission driving elements from the motors to the cutting head. It will be realized that the cutting head is a large rotatable unit having cutting teeth about the periphery thereof and that the motors which drive it, usually electric motors, are very large motors in the order of several hundred horsepower. First and second hydraulic rams or cylinders are coupled to the frame assembly for moving it upwardly and downwardly across the face of the material to be mined whereby the cutting head removes the material from the mine face as the frame assembly is moving the cutter head upwardly or downwardly. Obviously, the horizontal motion of the cutting head can be controlled by steering the mining machine itself.
Because of the large size of the cutting head, the drive motors and the mechanical transmission coupling the two, and because of the tremendous stresses which are placed on the various components in the mining of material such as anthracite coal, the components of the mining machine, and in particular the cutting head, the drive motors and the mechanical transmission, are subject to wearing or breakage and from time to time need to be repaired or replaced.
The problem with the prior art mining machines in this respect is that the entire pivotable frame assembly including the cutting head, the drive motors and the transmission linkage, has to be removed from the mining machine and taken to the earth's surface outside the mine for repair. This occurs because the frame assembly and the elements attached thereto are formed as an integral unit and therefore when the cutting head assembly has to be removed, the transmission linkage and drive motors must also be removed. This, of course, requires the need for special equipment and so the entire frame assembly has to be removed from the mining machine and taken to the surface where special tools can be available to separate the integral components and repair whatever is needed. As can be seen in U.S. Pat. No. 3,495,876, the mining machine disclosed therein has a cutting head assembly disposed at the outer end of a frame assembly and is driven by electric motors through a gear linkage as shown in FIG. 4 thereof. The integral construction of the unit does not allow the disassembly of the cutting head unit without also disassembling the transmission assembly which couples the drive motors to the cutting head. Such a mining machine assembly is also disclosed in U.S. Pat. No. 3,516,712 which also has the same problem.
The present invention overcomes the disadvantages of the prior art by providing a mining machine with a frame assembly having a cutting head assembly which is removably mounted or attached to the outer end of the frame assembly whereby the cutting head can be separately removed from the frame assembly of the mining machine where the mining is taking place.
In addition, the cutting head is itself formed of a shaft having at least one bearing attached thereto and at least one drive gear attached thereto. The cutting elements are formed in cylindrical segments and encircle and are rigidly attached to the shaft. A split housing is formed on the outer end of said frame assembly with one-half of the housing being integrally formed as part of the frame and the other half of the housing being removably attached to the frame assembly about the shaft bearings so that the shaft is carried by the bearings at the front end of the frame assembly. If two motors are used to drive the shaft, then two bearings are formed on the shaft and each one is held in a corresponding split housing. First and second intermediate cutting elements having cutting bits rigidly attached to the outer surface or periphery thereof which encircle the shaft as well as the bearing housings so that the bearing housings are totally located within the first and second cutting elements. The third and fourth cutting elements are also cylindrical in shape and encircle the shaft and are rigidly attached to the outer ends of the first and second cutting elements respectively. The third and fourth cutting elements also have cutting bits rigidly attached to the outer periphery thereof.
The drive gear on the cutting head shaft is driven by the drive motor gear through an idler gear. An end cap is formed over each of the drive gears attached to the cutting head drive shaft to form a sealed housing in which the drive gear is protected while it rotates.
Since no rotation of the cutting heads can take place over the end cap covering the drive gear on the cutting head drive shaft, first and second sprockets are placed on the sides of the end cap covering the drive gear and are rigidly attached to the shaft. An endless chain is driven by the sprockets and is carried at the other end by a roller or an idler sprocket and cutting bits or teeth are placed on the chain so that the entire cutting head has a continual cutting surface.
The idler gear which couples the drive motors to the gear on the cutting head shaft is mounted on an eccentric collar about a rigid shaft. When the eccentric collar is placed in a first position, it allows the idler wheel gear which is placed thereon to couple the motor driving gear to the shaft driven gear with a particular gear ratio and thus allows the cutter head to be driven at a particular speed for any given RPM of the drive motor. If the eccentric collar is rigidly attached in a second position, it allows a larger idler gear and a smaller size motor driving gear to be installed to cause the cutter head shaft driven gear to achieve a different speed of rotation. Thus, the cutting head assembly obtains a different rotational speed for the same given RPM of the drive motor.
Thus, it is an object of the present invention to provide a mining machine which has a cutting head that can be disassembled and repaired in the location where the mining is taking place.
It is also an object of the present invention to construct the cutting head in segments that can be individually removed so that disassembly of the unit at the location where the mining is taking place is relatively simple.
It is still a further object of the present invention to provide an improved mining machine in which the cutting head speed can be changed simply by changing the size of the motor drive gear and the idler gear coupled to the cutter head drive gear through the use of an eccentric collar placed about a rigid shaft for the idler gear.